Like humans, baboons with tough childhoods die earlier

By Karin Brulliard

April 26, 2016 — 11.48am

People who experience trauma during childhood– abuse, neglect or divorce, for example– are more likely to be less healthy adults who die at earlier ages. Several studies have found that. But it has been difficult for scientists to determine whether early adversity leads to those health problems and premature deaths, or whether they're attributable to other things more common among adults who had tough childhoods, such as a lack of access to medical care or drug use.

A new study published in Nature Communications found that childhood stress leads to early death even in the absence of those other complicating factors – in wild baboons, at least. But the researchers who conducted it think it suggests that the same might be true for humans, whose DNA is 94 per cent similar to baboons'.

The early loss of a mother and having a close-in-age younger sibling are particularly tough for baboons.

To reach this conclusion, a team of researchers from Duke University, Princeton University and the University of Notre Dame turned to a population of baboons in Kenya's Amboseli National Park that has been observed almost daily for 45 years.

They zeroed in on 196 female baboons – males roam, and so make for more difficult study subjects – and tallied up how many of six kinds of childhood adversity each had experienced. Among the childhood setbacks considered: drought in the first year; loss of a mother before age 4; and a sibling less than 1.5 years younger, which can divert a mother baboon's attention.

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Baboons that experienced three or more kinds of adversity had a life expectancy 10 years shorter than those that experienced one or none. Credit:AP

The findings were stark. The baboons that experienced three or more kinds of adversity had a life expectancy 10 years shorter than those that experienced one or none. The unlucky baboons also had fewer surviving offspring and were more socially isolated from other females in adulthood, according to the researchers, who wrote that those animals "paid a cost both in years of their own lives and in lifetime reproductive success".

The early loss of a mother and having a close-in-age younger sibling are particularly tough for baboons, the study found, because "maternal investment" is so important to the animals when they're young.

That's sad for those baboons. But it may be illuminating for humans. Because baboons don't rely on health insurance or speedy ambulances, and they don't binge on beer or snort cocaine, many variables at play in studies on the effects of childhood trauma in people weren't in this one.

"When you pick up parallels like the ones we're talking about in this study, it suggests there's something fundamentally biological about the relationship between early life adversity and later life health and survival that can't be explained by differences in health habits and access to health care," Jenny Tung, an assistant professor of environmental anthropology and biology at Duke, told a Duke publication.